Resistor assembly with compression plate supports

ABSTRACT

A non-inductive resistor for an oil circuit breaker is formed of pancake coils stacked atop one another and held compressed against one another by a central support rod.

United States Patent 1 l 3,737,831 Rietz et al. [4 June 5, 1973 RESISTORASSEMBLY WITH References Cited COMPRESSION PLATE SUPPORTS UNITED STATESPATENTS [75] Inventors: Earl B. Rietz, La Canada; James R. 2 407 I7]9/1946 Mcparren 338,261 x Burbafki 2:558:798 7/1951 Thom ..338/3l5 xAlhambra P 3,213,402 10/1965 Tassara ..338/260 Pasadena, all of Calif.

[73] Amiigncci l-T-E Imperial Corporation, FOREIGN PATENTS ORAPPLICATIONS Philadelphia, Pa.

' ..3 8 260 Filed: Oct. 12,1970 858,117 l/1961 Great Bntain 3 [21] Appl.No.: 80,109

Primary ExaminerE. A. Goldberg Related Apphcauon Data Attorney-SamuelOstrolenk, Sidney G. Faber, [62] Division of Ser. No. 764,975, June 7,1968, Pat. No. Bernard Gerb 3,560,905, which is a division of Ser. No.439,304, March 12, 1955, Pat. No. 3,392,248. 1 ABSTRACT A non-inductiveresistor for an oil circuit breaker is 333/295, formed of pancake coilsstacked atop one another and 338/320 held compressed against one anotherby a central suplnt. Cl. ..H0lc part rod [58] Field of Search ..338/260,261, 295,

3 Claims, 23 Drawing Figures Patented June 5, 1973 6 Sheets-Sheet 1Patented June 5, 1973 3,737,831

6 Sheets-Sheet 5 6 Sheets-Sheet 4 Patented June 5, 1973 6 Sheets-Sheet 5m. G U QNRN (kw -fiw -I N Pmmd June 5, 1913 6 sheets-sheet'e RESISTORASSEMBLY WITH COMPRESSION PLATE SUPPORTS This application is a divisionof copending application Ser. No. 764,975, filed June 7,1968, now USPat. No. 3,560,905, in the name of Earl B. Rietz et al., entitledRESISTOR STRUCTURE FOR OIL CIRCUIT BREAKER INTERRUPTER. Application Ser.No. 764,975 was, in turn, a division of application Ser. No. 439,304,filed Mar. 12, 1965, now US Pat. No. 3,392,248, in the name of Earl B.Rietz et al., entitled INTERRUPTER STRUCTURE HAVING CON- TOURED ARCSPLITTER PLATES AND SEPA- RATELY HOUSED- RESISTOR CONTACTS AND RESISTORSTRUCTURE THEREFOR, both of which are assigned to the assignee of thepresent invention.

This invention relates to oil circuit breakers, and more specificallyrelates to a novel interrupter structure including their parallelresistors for oil circuit breakers.

A first feature of the present invention is in the novel arrangement ofthe arc splitter plates of the interrupter.

Thus, an important object of the invention is to provide a novelsplitter plate wherein the are drawn within the interrupter is closelyconfined, and cannot move along the face of the splitter plate.

A further object of this invention is to provide a novel constructionfor are splitter plates wherein sections thereof are reduced inthickness to provide shallow oil reservoirs in close proximity to thearc path.

Another object of this invention is to provide a novel are splitterplate which has a peripheral ridge which prevents arc exhaust productescape from any direction other than toward the exhaust opening in theinterrupter container.

Another object of this invention is to provide a novel port and bafflearrangement for the plates of the interrupter chamber of an oil circuitbreaker.

As is well known to the art, it is often useful to provide an auxiliaryimpedance circuit in parallel with the main contacts of an oil circuitbreaker interrupter. However, where such parallel connected impedancesare used, it is necessary that when the main contacts are disengaged,the parallel path through. the impedance elements be similarlydisengaged.

A further important feature of the present invention provides a novelauxiliary contact arrangement whereby the parallel connected impedancecircuit is opened when the main movable contact of the interrupter movesout of the interrupter chamber. More specifically, the present use ofspring-tempered contact fingers mounted on the bottom lug of theinterrupter tube and connected to one end of the impedance is avoidedand replaced by a novel contact finger arrangement wherein separatecontact fingers mounted in a novel manner are biased toward engagementwith the contact rod. These contact fingers are then carried from acommon conductive spring carrier which is, in turn, electricallyconnected to one. end of the parallel connected impedance.

Accordingly, another important object of this invention is to provide animproved auxiliary contact arrangement for parallel connected impedancesassociated with interrupter structures.

Another object of this, invention is to provide a novel auxiliarycontact arrangement for interrupters which will not interfere with thenormal function of the inter- I rupter.

Yet another object of this invention is to provide a novel auxiliarycontact arrangement which operates satisfactorily for long periods oftime.

A still further object of this invention is to provide a novel auxiliarycontact arrangement for interrupters wherein external connection toimpedance elements may easily be made.

As indicated above, impedance elements connected in parallel with themain interrupter contacts operate to improve interruptioncharacteristics. Such impedance elements are'normally resistors.

Another important object of this invention is to pro vide a novelarrangement for these resistors wherein resistor coil layers are woundabove one another and are clamped together by a central insulation rod.

Another object of this invention is to provide a novel pancake resistorarrangement which provides easily accessible electrical connections ateach end thereof.

A further object of this invention is to provide a novel structuralarrangement for a pancake resistor which permits heat expansion of theunit and prevents free entrance of carbon into the unit.

A still further object of this invention is to provide a novel pancakeresistor structure which may be easily assembled.

In the performance of resistors for interrupter structures, it ispreferable to use a non-inductive resistor. Such resistors are commonlyformed by winding the layers of resistance wire in alternate directions.

It is a further important object of this invention to provide a novelstructure for permitting the simplified manufacture of a non-inductiveresistor having layers of resistance wire wound in alternate directions.

A further object of this invention is to provide a novel non-inductiveresistance structure.

These and other objects of this invention will become apparent from thefollowing description when taken in connection with the drawings, inwhich:

a FIG. 1 shows a top plan view of an interrupter structure and thehousing for its parallel connected resistor.

FIG. 2 is a cross-sectional view of FIG. 1 taken across the lines 2 2 inFIG. 1.

FIG. 3 is a cross-sectional view of FIG. 2 taken across the lines 3 3 inFIG. 2, particularly to illustrate the novel auxiliary resistorcontacts.

FIG. 4 is a cross-sectional view of FIG. 3 taken across the lines 4 4 inFIG. 3, and particularly illustrates a novel resistor mounting structureof the invention.

FIG. 5 is an exploded perspective diagram to particularly illustrate thenovel auxiliary contact structure.

FIG. 6 is a front plan view of the interrupter container of FIG. 2, andparticularly illustrates the placement of ports in the container.

FIG. 7 is a perspective view of one of the novel splitter plates of thepresent invention.

FIG. 8 is a top view of the plate of FIG. 7.

FIG. 9 is a front plan view of the plate of FIG. 8.

FIG. 10 is a cross-sectional view of the plate of FIG. 8 taken acrossthe lines 10 10 in FIG. 8.

FIG. 11 is a bottom view of the top plate of FIG. 2.

FIG. 12 is a cross-sectional view of the plate of FIG. 11 taken acrossthe lines 12 12 in FIG. 11.

FIG. 13 is a top view of one of the interrupter plates of theinterrupter of FIG. 2.

FIG. 14 is a cross-sectional view of FIG. 13 taken across the lines 1414 in FIG. 13. v I

FIG. '15 is a side view of the resistor structure to illustrate themanner in which the resistor wire is noninductively wound.

FIG. 16 is a plan view of the resistor of FIG. 15 seen from theleft-hand side.

FIG. 17 is a plan view of the resistor of FIG. 15 seen from theright-hand side.

FIG. 18 is an exploded perspective view schematically illustrating themanner in which the plates permit simple non-inductive winding of theresistance wire.

FIG. 19 schematically illustrates the winding of the first layer ofresistance wire.

FIG. 20 schematically illustrates the winding of the second layer ofresistance wire.

FIG. 21 schematically illustrates the winding of the third layer ofresistance wire.

FIG. 22 schematically illustrates the winding of a fourth layer ofresistance wire.

FIGS. 23a through 23r show 16 plates respectively in the order in whichthey are stacked for the novel resistor structure.

Referring first to FIGS. 1 through 14, the novel interrupter chamberstructure shall'first be described.

As shown in FIGS. 1 and 2, the complete structure will be supported froman upper conductive casting 30 which can be suitably secured to the endof an electrical bushing. This electrical bushing extends through themain support tank (not shown) which contains oil in which the completeinterrupter structure is immersed.

The interrupter includes an insulation casing 31 which is suitablyconnected to the casting 30. More specifically, a ring 32 is threadablyreceived by internal threads in the interior of casing 31. A pluralityof bolts, such as bolt 35 (FIG. 2), then pass through openings in theflange of casting 36 and into threaded openings in ring 32.

An internal portion 40 of the upper end of tube 31 is threaded asillustrated, and receives pressure ring 41. A metal spring ring 34electrically connects ring 40 and casting 30 to a pressure ring 41 toprevent corona noise from ring 41. The pressure ring 41, which ismetallic, bears against an insulation spacer ring 42 which seats upon agasket 43 contained around the periphery of the top spacer plate 44. Thetop plate 44 is shown in more detail in FIGS. 11 and 12, and it will beseen that this plate has a keyhole-shaped opening 45a therein. The plate44 then bears against a splitter plate 45 which, in turn, bears againsta splitter plate 46.

The splitter plate 45 is shown in more detail in FIGS. 7 through andwill be referred to more fully hereinafter. Note that splitter plates 45and 46 are of the male-female variety insofar as the engagement of theirouter peripheries are concerned, but are essentially identical to oneanother. The plate 46 then bears against a spacer plate 47 which isshown in more detail in FIGS. 13 and 14, and which has an opening 48therein.

A second pair of plates 49 and 50, which are identical to plates 46 and45 respectively, are then placed in position and a spacer plate 51,identical to plate 47, is immediately under plate 50. A third pair ofplates 52 and 53, which are identical to plates 45 and 46, are thencaptured between plate 51 and a plate 54 which is identical to plates 47and 51.

All of the plates 44 through 54 are of any suitable insulation materialsuch as vulcanized .fiber, or the like.

A spacer ring 55a isthen positioned below plate 54 and is generallyseated atop an auxiliary contact structure 55 which will be describedmore fully hereinafter, which is, in turn, captured by a throat bushing56 which is contained within the lower restricted portion 57 of the tube31.

The throat bushing 56, which is of a suitable insulation material,preferably has a conductive coating on the exterior surface thereof sothat it will not be deteriorated by the occurrence of corona dischargeover its surface.

It is to be understood that all of the plate elements are held togetherby means of the tightening of the spacer ring 41 which presses theelements against the bushing 56. Note that the elements are furtherkeyed with respect 'to one another as by suitable keying notches such asnotches 60 (plate 47, FIG. 13), 61 (plate 45, FIG. 8), and 62 (plate 44of FIG. 11) which cooperate with a key running along and extending fromthe interior of the tube 31.

It will be further noted that the pairs of splitter plates 45-46, 49-50and 52-53 define channels which extend to exhaust ports in the tube 31.Thus, plates 45 and 46 define channels 70, 71 and 72 which are incommunication with ports 73, 74 and 75 respectively in container 31. Ina similar manner, the plates 52 and 53 define channels leading to ports76, 77 and 78 respectively in tube 31.

The centrally disposed plates 49 and 50, as best seen in FIG. 6, definechannels similar, for example, to channel 70, 71 and 72 which lead toports 79, 80 and 81 which are angularly displaced from the line of ports73 through 78. This arrangement of displaced ports permits the directionof exhaust products during are interruption toward areas of the tankwhich are the furthest removed from the walls of the tank. Moreover, itpermits improved dispersion of the arcing products and of the reactionforce of the arcing products on the interrupter structure.

The main contacts of the interrupter include a movable elongatedrod-type contact schematically illustrated in dotted lines in FIG. 2 asthe rod contact 90. This contact is carried in the well-known manner ona conductive cross-bar, and passes through aligned openings in bushing56 and the various plates within the interrupter to engage a circularcluster of stationary contact fingers in the stationary contactstructure 91.

The stationary contact structure 91 is more specifically composed of acontact carrier 92 to which a plurality of contact fingers such ascontact fingers 93, 94, 95 and 96 are secured. The contact carrier, orhub 92, further carries an elongated arcing contact finger 97 whichextends lower than the remaining contact fingers and is the finger towhich an arc is drawn when the movable contact 90 is withdrawn from thestationary contacts. Each of the contact fingers 93 through 97 aretypically secured to the contact hub 92 as through a main flexibleconductor 98 and a pair of biasing springs 99 and 100, all of which areconnected to the contact hub 92 by suitable mounting bolts such as bolts101 and 102. The ends of springs 99 and bear on insulation buttons 103and 106 respectively to prevent the formation of a current carrying paththrough the springs 99 and 100.

The contact hub 92 is then bolted directly to the member 30 as by acentral bolt 105 with a keying membet such as key 106a insuring properalignment of contact hub 92 so that the arcing finger 97 is properlylocated within the casing 31. Itwill be seen that the elongated arcingfinger 97 is positioned within the elongated portion of keyhole slot 45in plate 44.

The operation of devices described to this point is as follows; When themovable contact 90 is withdrawn from the stationary contacts 91, an arcis drawn to arcing contact 97. This are causes the decomposition of oiland generates high pressure within the interrupter. This causes the highspeed movement of arcing products as well as fresh oil through thechannels such aschannels 70, 71 and 72, and out through the ports suchas ports 73 through .81 (FIGS. 2 and 6); this stream of oil and arcingproducts passing through the arc, thus causing the extinction of thearc.

An important feature of the present invention lies in the formation ofthe arc splitter plates 45, 56, 49, 50, 52 and 53. More particularly,and as best shown in FIGS. 7, 8, 9 and 10,- the plates have elongated.U- shaped openings such as the opening 110 which acts as a large oilreservoir disposed immediately behind the working face 1100 of thesplitter and leads to restricted passages 111 on the one side of theplate and 112 (FIG. 10) on the other side of the plate.

Regions such as regions 114 and 115 are thickened portions, whileportions 116 and 117 are relatively thin compared to sections 114 and115.

The U is disposed in line with the cross-phase axis of the breaker withthe sidesof the U closed-in to be par.- I

allel in order to be closely confining on the arc ,to prohibit sidewaymotion of the arc column.

Disposed on either side of this open reservoir 110 are volumes 11% and11 0c formed between adjacent plates (either two adjacent plates ofFIG/8 or one plate of either FIG. 11 or 13). By thinning down the inwardsections of the splitter plate (from the thickness required in thefrontor exhaust section as dictated by requirements of exhaust area andform), these secondary reservoir pockets are formed, disposed eitherside of and in close proximity to the intended arc position, along face110a.

By thinning the splitter down at section 110a (FIG. 8) to be less thanat section 111 (FIG. 8), the gap between adjacent faces is improved ormade larger in areas away from the intended arc path than the gap acrosssplitter-to-splitten in the intended arc path. This improves insulationwithstand capability across the enlarged gaps. If the interrupter gap isgoing to fail to recover voltage following a current zero, it is thusmore likely to fail across the'minimum insulation gap and thusreestablish currentin the region of the intended arc path.

The splitter plates, as shown in FIGS. 7 and 8, are fashioned with theexhaust port displaced from the cross-phase axis by an angle which is ofthe order of 40. By stacking said splitters alternatively in the variouspositions in the overall baffle assembly within the' interrupter tube, adivergent port assembly is achieved, as shown in FIG. 6, in which ports73, 7,4, and 75 are aligned in one position. Ports 79, 80, and 81 aredisplaced clockwise (viewed from top) with respect to them, and ports76, 77, and 78 next adjacent vertically are displaced counterclockwisewith respect to ports 79, 80, and 81. This resulting divergence servesto displace and divorce exhaust gases from adjacent interruptingsections to limit the possibility of electrical breakdown occurringoutside the interrupter chamber from gas bubble to gas bubble of ionizedgases; split the exhaust gases into smaller bubbles than with asingle-inline row of gases to permit more rapid cooling and dissipationof ionized are products; direct exhaust gases to either side of thespace between the interrupter and the oil tank in which insulationclearance in the oil is a minimum. Thus the divergent exhaust acts toretain greater integrity of insulation between live parts and thegrounded steel tank during the interrupting process.

As a further important feature of the present splitter plates structure,it has been found that the arc will be more rigidly confined in positionand will not move along the face of the splitter plates, as hasbeen'found in the past with other types of plate structures.

Finally, the plate is provided with peripheral ridges such as ridges 120and 121 (FIG. 10) which serve to prevent the escape of exhaust gasesfrom regions other than the exhaust openings 111 and 112.

It will be noted that plates 45, 50 and 52 are identical to one anotherand differ from plates 46, 49 and 53 only in the arrangement of theperipheral edges. That is to say, they are arranged as male and femaleplates.

It is to be further noted that the keying notches in plate 49 and 50will be angularly displaced from the keying notches in plates 45, 46, 52and 53 so that the appropriate passages of plates 49 and 50 will besuitably aligned with the ports 79, and 81 of FIG. 6.

As previously indicated, it is often desirable to connect a suitableimpedance in parallel with the main interrupter contacts (movablecontact and stationary contact 91) to improve the operation of theinterrupter. It is, however, necessary to interrupt this auxiliaryimpedance circuit after interruption is accomplished at the maincontacts.

The present invention provides a novel auxiliary contact arrangementwhich engages the movable contact rod 90 so long as the contact 90 iswithin the throat bushing, and is disengaged when the contact 90 leavesthe throat bushing. This novel auxiliary contact arrangement is bestshown in FIGS. 2, 3 and 5.

Referring now to these figures, it is seen that the throat bushing 56has positioned thereon a metallic disk 130. This disk is then secured toan upper cap 131 and is secured thereto by means of suitable screws suchas screws 132, 133, 134 and 135. The plate 130 and cap 131 capture astationary conductive block 136 which is seated upon a U-shapedconductive spring 137 and is secured to cap 131 by a bolt 138. The endsof spring 136 are then connected to the contact segments 151 and 152respectively by suitable securing means such as screws 153 and 154respectively. The contact segments 153 and 154 have a height less thanthe interior spacing between cap 131 and disk 130, and receive biasingsprings such as compression springs 155 and 156 respectively which seatupon the interior of cap 131. Thus, the contact segments 151 and 152 arenormally biased toward one another.

The total movement of contact segments 151 and 152 is restricted topredetermined limits by means of inserts 157 which hasmovement-restricting notches 158 and 159 therein which receive portionsof segments 151 and 152 respectively. Any suitable electrical connectionis then made to the screw 138 or, for example, to the cap 131, thisconnection being taken externally of tube 31.

As will be seen more fully hereinafter, the mounting screws 160 and 161for the resistor assembly, to be described, are threaded into tappedopenings in cap 131, and thus form the lower terminal for the resistorwhich is connected in series with the auxiliary contacts 151 and 152.

In operation, it is clear that when the contact rod 90 of FIG. 2 entersthe interrupter structure, the segments 151 and 152 will be cammedoutwardly against the force of their bushing springs 155 and 156respectively so that good contact pressure is had between the contactrod 90 and contact segments 151 and 152. When the movable contact rod 90is then moved to its disengaged position, and before contact 90 hascleared the bottom of the interrupter, any parallel connected impedanceelement connected to contacts 151 and 152 will be connected in parallelwith the are drawn between the main contacts.

Assuming now that the arc has been suitably extinguished and the contactrod 90 clears the bottom of the bushing 56, the contact 90 willdisengage contact segments 151 and 152, thus opening the auxiliarycircuit. Note that the contact segments 151 and 152 have only a limitedpermissible inward motion as determined, for example, by stops 158 and159 so that the contacts do not collapse inwardly when the contact rod90 is withdrawn.

It is to be specifically noted that the insulation spacer 55a which iscarried above cap 131 of FIG. 2 defines an oil reservoir above theresistor contact 151 and 152. This novel oil reservoir decreases thechance of interrupting gases extending to the resistor contacts duringthe interruption operation. Moreover, it will be noted that the resistorcontacts 151 and 152 are, in effect, completely encased in a metallichousing which includes plate 130 and cap 131 which each have roundededges. This forms a uniform electrical field across the power gap anddecreases corona and splitting of insulation member edges.

FIGS. 1, 3 and 4 additionally show a novel resistor structure which canbe used as the parallel connected impedance member for the interrupterof FIG. 2. More specifically, a resistor structure generally shown bynumeral 180 in FIG. 1 is suitably secured to the interrupter structureof FIG. 1 with the upper terminal of the resistor connected to member30, and the lower terminal of the resistor connected to the resistorcontacts 151 and 152.

This resistor structure is formed in the novel manner particularly shownin FIG. 4, and includes a stack of resistor elements 181, which will bedescribed more fully hereinafter, which are-contained within aninsulation tube 182. The tube 182 receives a plate 183 which may bemetallic which is prevented from moving upwardly by means of a splitinterference ring 184 contained in a suitable groove in casing 182. Anupper conductive housing or support 185 is then connected to plate 183by suitable screws such as screws 186 and 187 (FIGS. 1 and 4). The upperhousing section 185 has an upwardly extending flange section 187a (FIGS.1 and 4) which receives bolts such as bolts 188 which serve to bolt thesupport member 185 directly to suitable portions of upper member 30 ofthe interrupter structure.

The lower portion of the resistor structure of FIG. 4 includes a lowerplate 189 which bears against the bottom of the resistor stack 181 andwhich is prevented from moving out of the tube by a suitable splitinterference ring 190. The bottom of casing 182 is then received by asuitable conductive support 191 which, as best shown in FIG. 3, issecured to the bottom of the interrupter housing by screws and 162 whichfurther serve to electrically engage the resistor contacts 151 and 152.

In order to hold the resistor stack 181 together dur' ing assembly, awooden rod or other suitable insulation rod 200 extends through thecomplete resistor housing and is terminated at either end by nuts 201and 202 respectively. The plate 189 then seats atop a spring 203 whichexternally surrounds the lower end of rod 200 and its lower nut 202. Atthe upper portion of the structure, a pressure plate 104 bears atopstack 181 and receives a compression spring 205 which has its other endin engagement with the plate 206 which is carried within a suitableaperture in upper housing portion 185.

This novel structural arrangement permits the rod 200 to be in tensiononly during assembly of the device and removes any support function fromthe rod 200. The complete support for the resistor structure comes fromthe casing 182 and its upper and lower supports and 191.

In order to assemble this novel structure, the resistor pack 181 isfirst inserted into the tube 182; the plate 183 and its interferencering 184 and the support 185 having been previously assembled in a loosemanner by the screws 186. This permits the lower split interference ringto be inserted into tube 182. The screws such as screw 186 are thentightened, which pulls the support 185 downwardly and into engagementwith the upper end of tube 182. At the same time, spring 205 iscompressed, and forces the resistor stack 181 downwardly until plate 189engages interference ring 190.

Accordingly, the structural mounting, as indicated previously,completely relieves the wooden insulating rod 200 from the stringmechanical forces, as would occur during a short circuit interruptionoperation.

The electrical circuit for the system partly extends from housing 191which is appropriately connected to the terminal 220 through plate 189and spring 203. Note that the terminal 220 could be connected to theresistor contacts 151 and 152 in any desired manner other than throughthe housing section 191.

The upper end of the resistor pack terminates in terminal 221 which, bymaking plate 204 of metallic material, is electrically connected throughspring 205 and metallic plate 206 to the metallic upper housing 185 andthence to the upper conductive housing 30 of the interrupter.

In order to permit oil circulation through the resistor structure,bottom slots such as slots 225 are provided in the lower plate 189 andthrough openings 226, 227 and 228. Note that the uppermost opening 228is so arranged in the side of upper housing 185 that carbon and othersimilar impurities floating in the circuit breaker oil will not easilysettle into the resistor structure.

The main purpose of nut 201 is to hold the resistor pack together whenit is removed from the tube 181. Thus, the complete resistor pack, alongwith plates 189, 204, 183 and 206, serve as a subassembly of theresistor structure.

It is to be particularly noted that prior art resistor devices utilizethe central rod 200 as the main structural member for carrying theresistor structure from the interrupter. Thus, the rod necessarilybecomes very large which, in turn, enlarges the complete unit.

The manner in which the resistor package 181 is formed is particularlyshown in FIGS. through 22. The assembly of the resistor of FIGS.15through 22 will be recognized as the resistor structure removed fromits housing 182 in FIG. 4. Note particularly that the spring 203 iscaptured by lower nut 202 by means of a square sheet 250 of FIGS. 15 and16 whose corners are folded over, as shown in FIG. 16, to capture spring203.

It is extremely desirable that the resistor used as the parallelimpedance for the interrupter of the invention or of other similarinterrupter equipment be of a noninductive nature. Non-inductiveresistors are generally well known, and are formed by winding aresistance wire in several layers with alternate layers, for example,being wound in opposite directions. In this manner, the magnetic fieldsinduced in adjacent layers oppose one another so that the inductance ofthe coil is negligibly small.

Present arrangements for achieving the opposite winding direction foralternate layers of resistance wire are extremely awkard, timeconsuming, and the wire cannot be wound directly from a wire spool. Thenovel resistor structure shown in FIGS. 15 through 22 is one in which anon-inductive resistor can be wound directly from a wire spool with thecoils or adjacent layers being suitably separated to keep creep voltagestress for between'layer cross-overs below a safe maximum value.

In accordance with the invention, each layer of resistance wire isassociated with aset of spacers and plates wherein the spacers andplates have suitable notches therein for permitting placement andwinding reversal of the resistor wire which is woundfrom a single spool.Moreover, the spacers and plates for adjacent layers are 90 displacedfrom one another which permits a similar displacement at thebetween-layer cross-over to keep voltage creep stresses to a minimum.

In FIGS. 15 and 19 through 23, I haveillustrated the formation of thefirst four layers of the resistor, it being understood that the completeresistor will be formed in an identical manner.

Referring now to FIG 15, there is shown four groups 260, 2 61, 262 and263 respectively of three plates and a winding plate each. The groups260 through 263 are shown in FIGS. 19 through 22 respectively. Each ofthe stacks 260 through 263 are formed of plates, best shown in FIG. 18for the case of stacks 260 and 2 61 in exploded perspective view.

The individual plates of stacks 260 through 263 are further shown inFIGS. 230 through 23r, which are in the order in which the platesarestacked. Each of the plates are mounted on the square wooden shaft200. The group of plates 260 is shown in FIGS, 2311, b, c and d, andincludes a winding plate 270, first and second slotted plates 271 and272, which are identical in construction and contain narrow slots 273and 274 respectively, and notches 276 and 277 respectively, and acentral plate 278 which contains a V-shaped notch 279.

Each of the remaining groups are made up of similar plates to thoseshown in FIGS. 230, b, c and d, but are rotated clockwise by 90 withrespect to the plates of an adjacent group. This feature permitsapplicants novel displaced cross-over point in the resistance wind-FIGS. 15 through 23 is best understood from FIG. 18

for the case of the first two groups 260 and 261.

Referring particularly to FIG. 18, the resistance wire 290 is taken fromsome suitable spool, not shown. The

various plates such as plates 271, 278, 272 and 270 are then containedon the square wooden shaft 200 and the resistance wire 290 is placed inthe groove 276 of plate 271. This wire is then brought to the top of thesloping portion of V-shaped slot 279 and then rides down to the slot tothe bottom thereof. At this point, the wire extends over to the bottomof the narrow slot 274 and thence to the top surface of the windingplate or disk 270. The wooden shaft 200 is then rotated so that theresistance wire winds on plate 270 in the direction shown by the arrow291. Some predetermined number of turns are then formed on the plate 270to form a pancake-type resistance winding 292.

The next group of plates 261 have been assembled and are rotated by withrespect to the similar stack of plates 270. The end of pancake winding292 is taken from a point to the rear of the winding in FIG. 18, and isbent directly over into the notch 276 of plate 271 of group 261.

In a manner identical to that for group 260, the wire then enters theV-shaped slot 279a of plate 278a to the bottom of the slot and then overthrough the bottom of slot 274a of plate 272a. Thereafter, the wire isplaced immediately on the winding surface of plate 270a and the assemblyis rotated in such a direction that a pancake resistance winding 293 isformed with the wire winding in the direction of the arrow 294. Notethat winding 293 is wound oppositely to winding 292, whereby themagnetic fields generated by each of the windings when current flowpasses therethrough are in opposing directions, thus rendering these twowinding sections relatively non-inductive.

Clearly, this winding process continues until the end of the resistor isreached with the adjacent windings being wound oppositely from oneanother. Moreover, the points at which each of the windings terminatesand crosses over to the next group of plates are displaced with respectto one another by 90, thereby improving the voltage distribution acrossthe winding.

Although this invention has been described with respect to its preferredembodiments, many variations and modifications will now be obvious tothose skilled in the art, and it is preferred, therefore, that the scopeof the invention be limited not by the specific disclosure herein butonly by the appended claims.

The embodiments of the invention in which an exclusive privilege orproperty is claimed are defined as follows:

1. A resistor assembly including a resistor tube, a plurality of stackedresistor disks connected in series with one another within said tube andfirst and second terminals; said plurality of series connected resistordisks connected to said first and second terminals, upper and lowercompression plates on the upper and lower surfaces of said stackedresistor disks, and an upper and lower conductive support received bythe upper and lower ends respectively of said tube, and a central rodextending through said disks and said upper and lower compressionplates; said central rod being connected to said upper and lowercompressionplates and forcing them toward one another to hold saidresistor disks tosaid upper or lower compression plates: said one ofsaid upper or lower compression plates being connected to one end ofsaid central rod through said compression spring, the other of saidupper or lower compression plates being directly secured to the otherend of said central rod.

3. The device substantially as set forth in claim 1 wherein said lowercompression plate is captured in the lower end of said resistor tube bysnap ring means in the interior of said resistor tube.

1. A resistor assembly including a resistor tube, a plurality of stackedresistor disks connected in series with one another within said tube andfirst and second terminals; said plurality of series connected resistordisks connected to said first and second terminals, upper and lowercompression plates on the upper and lower surfaces of said stackedresistor disks, and an upper and lower conductive support received bythe upper and lower ends respectively of said tube, and a central rodextending through said disks and said upper and lower compressionplates; said central rod being connected to said upper and lowercompression plates and forcing them toward one another to hold saidresistor disks together; said upper and lower conductive support havingmounting means therein for mounting said resistor assembly; said centralrod being independent of a mounting function, and a second uppercompression plate spaced from said upper compression plate; said secondupper compression plate being directly secured to said upper conductivesupport; said second upper compression plate being captured by snap ringmeans in the upper end of said resistor tube.
 2. The devicesubstantially as set forth in claim 1 which includes a compressionspring adjacent one of said upper or lower compression plates: said oneof said upper or lower compression plates being connected to one end ofsaid central rod through said compression spring, the other of saidupper or lower compression plates being directly secured to the otherend of said central rod.
 3. The Device substantially as set forth inclaim 1 wherein said lower compression plate is captured in the lowerend of said resistor tube by snap ring means in the interior of saidresistor tube.